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A Wide Area Survey for High-Redshift Massive B z K Galaxies

A Wide Area Survey for High-Redshift Massive B z K Galaxies

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A Wide Area Survey for High-Redshift Massive B z K Galaxies

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  1. A Wide Area Survey for High-Redshift Massive BzK Galaxies Kong et al. (2006) ApJ 638, 72 N. ARIMOTO (NAOJ) X.Kong, M.Onodera, C.Ikuta (NAOJ), K.Ohta (Kyoto), N.Tamura (Durham), A.Renzini, E.Daddi, L. Da Costa (ESO), A.Cimatti (Arcetri), T.Broadhurst (Tel’Aviv), L.F.Olsen (Cote d’Azur)

  2. We have undertaken a fairly deep, wide-field imaging with the Subaru/Suprime-Cam of two fields of 900 arcmin2 each for part of which near-IR data are available from ESO NTT observations. EIS Deep 3a Survey Kong et al. (2006) ApJ 638, 72 The prime aim of this survey is to understand how and when the present-day massive galaxies formed. To this end, the imaging observations have been optimized for the use of optical/near-infrared multi-colour selection criteria to identify both star forming (sBzKs) and passive galaxies (pBzKs). EIS3a-F (Subaru/NTT, Ks=20.8) 320 arcmin2 Daddi-F (Subaru/NTT, Ks=19.0) 600 arcmin2

  3. Subaru/Sup-Cam Observation Daddi Field RA=14:49:29, DEC=09:00:00 (J2000.0) Subaru/Suprime-Cam BIz’: 2003/03/02-04 WHT R : 1998/03/19-21 NTT/SOFI K : 1999/03/27-30 BRIz’ (940 arcmin2) 3σ in 2”(AB) B(AB)=26.59 R(AB)=25.64 I(AB)=25.62 z’(AB)=25.31 K (600 arcmin2) 3σ in 2”(AB) Ks(AB)=20.91

  4. 600arcmin2 940arcmin2

  5. Subaru/Sup-Cam Observation ESO Imaging Survey (EIS Deep 3a) Field RA=11:24:50, DEC=-21:42:00 (J2000.0) Subaru/Suprime-Cam BRIz’: 2003/03/02-04 NTT/SOFI JK : 2002/03/28-31 BRIz’ (940 arcmin2) 3σ in 2”(AB) B(AB)=27.46 R(AB)=26.87 I(AB)=26.56 z’(AB)=26.07 JK (320 arcmin2) 3σ in 2”(AB) J(AB)=23.40, Ks(AB)=22.70

  6. 320arcmin2 940arcmin2

  7. High-z galaxies Deep 3a field Star-forming galaxies at z>1.4 (sBzKs) Old galaxies at z>1.4: (pBzKs) (z-K)>2.5 stars Daddi et al. (2004) ApJ 617, 746 BzK=(z-K)-(B-z)>-0.2

  8. SEDs of sBzKs and pBzKs

  9. Photometric Redshift star-forming passive high-z low-z

  10. Spectroscopic Redshifts (VLT) Daddi et al. (2006)

  11. pBzK(ERO) sBzK sBzK sBzK ERO ERO ERO ERO

  12. Star/Galaxy Separation (z-K)AB-0.3(B-z)AB<-0.5

  13. 387 sBzK 121 pBzK 513 ERO 108 sBzK 48 pBzK 337 EROs

  14. Photometric Redshift (EROs)

  15. Photometric Redshift (sBzKs)

  16. Photometric Redshift (pBzKs)

  17. Number Counts of sBzKs, pBzKs, and EROs galaxies pBzKs EROs sBzKs

  18. Two Point Correlation Functions w(Θ) Landy & Szalay (1993) Daddi-F Deep 3a-F

  19. Angular Clustering Amplitude

  20. Physical Properties of sBzKs and pBzKs • Supposing <z>~2 for sBzKs, we have derived their physical properties, such as the reddening, star formation rate, and the stellar mass. (While errors by a factor of 2 or more may affect individual estimates, the average quantities should be relatively robust.) • Reddening : E(B-V)=0.25(B-z+0.1)AB ←UV Continuum slope (Calzetti law) • SFR : SFR(Mo/yr)=L1500[erg/s/Hz]/8.85x1027 • Stellar Mass : log(M*/1011Mo)=-0.4(Ktot-20.14Vega)

  21. The filled area is the histogram for sBzKs which associated with X-ray sources (25%). The dashed lines are for the stellar mass histograms of pBzKs.

  22. MAMBO & Spitzer (MIPS) Observations of sBzKs at z~2 B B z z Dannerbauer et al. (2006) ApJ 637, L5 (Poster 14Dannerbauer)

  23. IR SFR ~ UV SFR sBzKs SMGs Local ULIRGs sBzKs(GOODS-N)

  24. Contribution of sBzKs and pBzKs to Stellar Mass Density at z=2 logρ*(total)=7.7 Mo/Mpc3 logρ*(total)=7.86 Mo/Mpc3 (1.5<z<2.0, Fontana et al 04) logρ*(total)=7.65 Mo/Mpc3 (2.0<z<2.5, Fontana et al 04) logρ*(total)~7.5 Mo/Mpc3 (@z~2, Dickinson et al 03) Number density of pBzKs with M*>1011Mo over the range 1.4<z<2.0 (1.8±0.2)x10-4Mpc-3 Local value of massive ellipticals at z=0 9x10-4Mpc-3 (Baldry et al. 2004) 25% AGN 20%±7% of massive (M*>1011Mo), passively evolving galaxies at z=0.

  25. Summary (I) – Number Counts • BzK selection is a quite powerful way to separate • high-z galaxies such as sBzKs, pBzKs and EROs • at 1.4<z<2.5. • Down to the K-band limit of the survey the log of the • number counts of sBzKs increases linearly with the • K-magnitude, while that of both EROs and pBzKs flattens • out by Kvega~19. • EROs are in a modest redshift shell (z~1), • while pBzKs are also in a relatively narrow • redshift shell but at higher redshift (z~1.5). • sBzKs are drawn from a large range of redshifts, • and their relative numbers increase sharply with redshift.

  26. Summary (II) - Clustering 2) The clustering properties of EROs and sBzKs are very similar, clustering amplitudes ~10 times higher than generic galaxies in the same magnitude range. This suggests an evolutionary link between sBzKs at z~2 and EROs at z~1, with star formation on sBzKs quenching by z~1 thus producing passively evolving EROs. The clustering amplitude of pBzKs is even higher than that of sBzKs and EROs, suggesting that quenching epoch of star formation in massive galaxies depends on environmental density.

  27. Summary (III) – Physical Properties 3) sBzK galaxies (KVega<20) have median reddening E(B-V)~0.40, average SFR ~ 190 Mo/yr, typical stellar mass ~1011 Mo, and ~solarmetallicity (Poster 44 Onodera). The high SFRs, large masses and high metallicities of sBzKs suggest that these z~2 star forming galaxies are the precursors of z=1 passive EROs and z=0 early-type galaxies. Mambo/MIPS observations suggest sBzKs are post ULIRGs.

  28. Summary (IV) – Number Density 4) The number density of massive pBzKs (KVega<20, M*>1011 Mo) is about 1/5 of similarly massive early-type galaxies at z=0. The quenching of star formation in massive star-forming galaxies must result in a significant growth since <z>~1.7 in the number of massive, passive galaxies. We argue that most of this star-formation quenching is likely to take place between z~2 and z~1.

  29. Massive Early-type GalaxiesEvolutionary Tracks (M*>1011Mo) z~0 z~1 z~2 z>2 E(B-V)~0.4 SFR~190Mo/yr Z~Zo irregular morphology Passive EROs Early-type Galaxies Dusty EROs SMGs sBzKs number density 1/2 40-200Myr strong clustering 0.5-1Gyr strong clustering Passive EROs pBzKs ? number density 1/5 sRjLs numberdensity 1 very very strong clustering strong clustering